It’s up to you to decide.

There’s this long discussion about subfolders vs subdomains for languages.

I would recommend you to look at your site and think of the following. In the long run, is this site having the same content and addressing my users the same way? Then you might want to use subfolders and href lang links letting google know about where is the ‘other language versions of this content within the site’.

But if you are addressing different content entirely to different users altogether, the same way Ikea or MC Donalds would, for example, have different country content, then you might want to consider subdomains or TLDs.

To me, every language is a different league, with a different set of competitors, and a different battlefield. The one domain/site umbrella might help in domain authority, but in enterprise cases, you might want to keep things extremely separated.

Take this with a pinch of salt; I’d love to hear what everybody else thinks out of this.